This invention relates generally to an electrophotographic printing device, and more particularly, a lubricating system in the cleaner apparatus that removes particles adhering to an imaging surface (i.e. photoreceptor or photoconductor).
In an electrophotographic application such as xerography, a charge retentive surface is electrostatically charged, and exposed to a light pattern of an original image to be reproduced to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on that surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image.
The latent image is developed by contacting it with a finely divided electrostatically attractable powder referred to as “toner”. Toner is held on the image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate (e.g. paper), and the image affixed to form a permanent record of the image to be reproduced.
Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. The process is well known, and useful, for light lens copying from an original and printing applications from electronically generated or stored originals, where a charge surface may be imagewise discharged in a variety of ways. Ion projection devices, where a charge is imagewise deposited on a charge retentive substrate, operates similarly. In a reproduction process of the type as described above, it is inevitable that some residual toner will remain on the photoconductor surface after the toner image has been transferred to the sheet of support material (e.g. paper).
It has been found that with such a process the forces holding some of the toner particles to the imaging surface are stronger than the transfer force and, therefore, some of the particles remain on the surface after transfer of the toner image. In addition to the residual toner, other particles, such as paper debris (i.e. Kaolin, fibers, clay), additives and plastic, are left behind on the surface after image transfer. (Hereinafter, the term “residual particles” encompasses residual toner and other residual debris remaining after image transfer.) The residual particles adhere firmly to the surface and must be removed prior to the next printing cycle to avoid it's interfering with recording a new latent image thereon.
Various methods and apparatus may be used for removing residual particles from the imaging surface. One such method and/or apparatus is the use of a cleaning blade. Blade cleaning involves the blade, normally made of a rubber-like material (e.g. polyurethane) which is dragged or wiped across the surface to remove the residual particles from the surface. Blade cleaning is a highly desirable method, compared to other methods (e.g. brushes and webs), for removing residual particles due to it's simple, inexpensive structure. To assure reliable and effective cleaning of the image surface, a certain amount of force, of necessity, must be applied to the blade to maintain the cleaning edge against the imaging surface with sufficient pressure to avoid allowing any particulate material on the imaging surface to slip pass.
On many printers and copiers the cleaning blade experiences blade failures associated with a lack of lubrication. The premature failures increase the unscheduled maintenance rates and the cost associated with a high unscheduled maintenance rate. The failures, which are hard failures (i.e. the customer can no longer use the machine), adversely affect customer satisfaction.
The following disclosures may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 4,395,113 to Buchan et al. discloses a method and apparatus for cleaning a photoconductive surface in order to remove toner particles dispersed in a liquid developer wherein a smoother-surface, resiliently deformable, yieldable roller means is compliantly engaged with the surface to be cleaned so as to form a generally concave, smooth-surfaced cleaning pad space from the photoconductive surface by a gap not exceeding the diameter of minimum sized toner particles. The yieldable roller means is rotated such that the surface of the concave, smooth-faced portion thereof moves in an opposite direction relative to the direction of movement of the photoconductive surface and at a velocity at least equal to that of the photoconductive surface.
U.S. Pat. No. 3,895,135 to Fleisig et al. discloses a precisely dimensioned liquid reservoir which is formed by selecting an open-celled, porous form material, saturating the foam with a suitable liquid and thereafter cutting or shaping the foam into the particular form required.